Claims
- 1. A fresh dough package comprising:
- (a) a generally cylindrical can having a cylindrical body wall comprising a kraft paper body stock layer in strip form wound into a helix with its mating side edges defining a helically extending butt joint,
- (b) a liner formed from flexible sheet material against the inside surface of the body stock layer and overlapping the inner edge of the butt joint in the body stock layer,
- (c) a removable label layer peelably bonded to the outside surface of the kraft body stock layer,
- (d) said label layer having means therein defining a lifting tab, said lifting tab providing a means for withdrawing the label from the surface of the kraft body stock layer,
- (e) a peelable particulate mineral coating layer bonded between the label and the kraft body stock layer,
- (f) the removal of the label causing at least a portion of the particulate mineral layer to peel away from the adjacent body stock layer and at least a portion thereof to remain adhered to the label layer thereby facilitating the removal of the label without the surface of the body stock layer adhering to the label,
- (g) the peel strength of the bond between the label and the kraft body layer being between about 0.1 and 0.5 pounds per inch width of the label and also being less than the tensile strength of the label, thereby allowing removal of the label intact at least from the area of the butt joint to weaken the butt joint by an amount which is uniform throughout its length whereby the butt joint will have uniform opening characteristics throughout its length to facilitate opening the container at the butt joint, and
- (h) a circular end closure member sealed to at least one end of the tubular body wall of the container.
- 2. A fresh dough package comprising:
- (a) a generally cylindrical can having a cylindrical body wall comprising a kraft paper body stock layer in strip form wound into a helix with its mating side edges defining a helically extending butt joint,
- (b) a liner formed from flexible sheet material against the inside surface of the body stock layer and overlapping the inner edge of the butt joint in the body stock layer,
- (c) a removable label layer peelably bonded to the outside surface of the kraft body stock layer,
- (d) said label layer having means therein defining a lifting tab, said lifting tab providing a means for withdrawing the label from the surface of the kraft body stock layer,
- (e) an adhesive layer bonded between the removable label layer and the kraft body stock layer, said adhesive having quick tack characteristics when freshly applied,
- (f) a second layer between the label layer and the kraft layer said second layer comprising a particulate mineral coating bonded between the adhesive and an adjacent layer whereby the removal of the label causes at least a portion of the mineral layer to peel away from the adjacent layer and at least a portion thereof to remain adhered to the adhesive layer facilitating the removal of the label without the surface of the body stock layer adhering to the label,
- (g) the peel strength of the bond between the label and the kraft body layer being between about 0.1 and 0.5 pounds per inch width of the label and also being less than the tensile strength of the label, thereby allowing removal of the label intact at least from the area of the butt joint to weaken the butt joint by an amount which is uniform throughout its length whereby the butt joint will have uniform opening characteristics throughout its length to facilitate opening the container at the butt joint, and
- (h) a circular end closure member sealed to at least one end of the tubular body wall of the container.
- 3. The package of claim 2 wherein substantially all of said second layer remains adhered to the adhesive layer after the label is removed.
- 4. The package of claim 2 wherein the mineral layer bonded to the adhesive comprises a clay coating.
- 5. The package of claim 4 wherein the clay coating comprises about 40 parts water and at least about 45 parts by weight of clay when applied.
- 6. The package of claim 1 wherein the label comprises a plastic resin film.
- 7. The package of claim 6 wherein the plastic resin film comprises a polystyrene film.
THE PRIOR ART
This is a continuation in part of application Ser. No. 561,132 filed March 24, 1975 and bearing the same title now abandoned.
The field of the invention is fiber dough cans.
The cylinder board presently being used as the body stock layer of peel open fiber cans for fresh dough products is sometimes referred to as single news vat line cylinder board. The cylinder board layer is roughly 0.026 inches thick and a hundred pounds basis weight. The structure of cylinder board is unique since it provides a high wet strength and has on its surface relatively short fibers of newsprint which are torn out when the label bonded to the surface of the board is lifted and removed for the purpose of opening the can. The fibers can be seen on the label as a thin dark layer. The supply sources of cylinder board are relatively limited and even though it is less expensive than kraft paper on a tonnage basis, its bursting and tensile strength is less for sheets of equal thickness. Accordingly, natural kraft paper of only 0.020 inches in thickness and 70 pounds per 1,000 square feet has the equivalent strength of 0.026 inch cylinder board. Moreover, because the cylinder board is made from recycled paper, its composition is often difficult to ascertain and contamination is a potential problem, an important consideration in the packaging of food with which the present invention is primarily concerned.
Heretofore it has been thought essential to employ cylinder board in fresh dough containers in spite of its shortcomings because of its unique ability to allow removal of the label by peeling it away from the underlying cylinder board as described above. Kraft paper does not have easy-to-remove fibers on its surface and thus cannot be substituted for the cylinder board. In prior fiber cans, peeling off the label opened the cans. Where removal of the label is not a requirement, kraft paper is traditionally used as the body stock material because it is superior to cylinder board in both tensile and burst strength. Examples are U.S. Pat. Nos. 3,510,050 and 3,165,985. However, neither of the containers described in these patents is at present in widespread commercial use as far as can be determined and in neither case is the label removed from the body wall during opening.
The major obstacle using kraft liner board up to the time of the present invention has been an inability to find a way to achieve consistent and reliable peeling back of the label material while at the same time providing sufficiently strong adhesion to keep the label bonded in place until removed by hand.
When a label is glued to kraft paper, a bridge or membrane of delaminated paper of ten remains across the butt joint in the cylinder board layer which prevents reliable opening of the can. At other times the kraft paper may peel off irregularly (delaminate) and a considerable amount of force may be necessary to remove the label which produces an erratic uncontrolled patter of torn paper. Accordingly, a primary objective of the invention is to provide a fresh dough container of the type described having a kraft paper body layer, a removable label with a provision for allowing the label to be consistently and reliably removed to expose the butt joint defined by the mating edges of the underlying kraft paper without the label tearing and deliminating so as to leave a membrane of paper over the butt joint.
A problem in the application of adhesive which allows a layer of adhered sheet material to be peeled away is the requirement in the present invention for sufficient instant adhesive bond strength to enable the composite tube as it is formed to pass through the forming and cutting system without coming apart. This strength is required in the first three seconds after the layers come together in the winding operation.
In the course of development of the present invention, attempts were made to control the surface of the kraft paper to regulate its adhesion to the overlying label. These attempts, however, met with failure. In the present development, adhesives known as low peel strength high sheer strength adhesive were also tried. They were also unsuccessful in the present application because they did not have enough strength to hold the can together through the winding and cut-off operation.
The major objects of the invention are: a) to provide an improved fresh dough can having a body layer formed from kraft paper with a provision to facilitate consistent and reliable removal of the label from the kraft body layer, b) reduced cost due to an increase in yield of the kraft body compared with that of a cylinder board can body, a reduction for example, on the order of about 25% of the cost of the container body, c) a package which is suited for manufacturing using existing equipment, d) a package which is reliable in operation and rugged in construction, e) an increase in the crimping strength between the can ends to the can sidewall to improve the air burst strength without the requirement of a flanged locking seam between the metal and the can wall, f) the ability to use a less expensive label than the paper and foil laminate traditionally used, g) the provision of an improved fresh dough package in which the label is better suited for printing than the laminative foil and paper presently used, improving the quality of reproduction, h) the provision for allowing removal of the label as easily as in previous cans but reliably maintaining the label in place during the life of the product, i) the ability to employ readily available materials, j) a container which is adapted for use with a variety and grades of kraft paper, k) the bond between the label and the body layer has enough instant strength to hold the can together through the winding and cut-off operation, l) a more specific object of one form of the invention is to provide a label with a specific surface treatment on its under side compatible with the adhesive used to bond the label to the can body.
US Referenced Citations (9)
Continuation in Parts (1)
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Number |
Date |
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561132 |
Mar 1975 |
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Patent Grant
4093073
